A servo press machine performs pressing using a servomotor as source power. That is, rotation of the servomotor is delivered to a crankshaft through a motor shaft having a gear and a reducer, and a slide is moved up and down through the crankshaft, thereby performing pressing. For this reason, a space for installing the servomotor in the press machine needs to be separately prepared, which is one obstructive factor for miniaturization.
JP 2001-62596 A (Patent Document 1) is an example of a background art for miniaturizing the servo press machine. Patent Document 1 discloses a configuration in which a servomotor having a radial-type hollow rotor is directly assembled with a crankshaft.